Measurement of bone density (measurement of density of minerals of bones) provides significant data for diagnosis of osteoporosis and a follow-up treatment of osteoporosis, and various types of bone density measuring devices have been suggested. Bone density is measured by a variety of methods, including a method using radiation such as an X-ray, a method using an ultrasound wave, and other methods.
Bone density measuring devices that measure the bone density of the calcaneus, the radius, the second metacarpal bone, a lumbar vertebra, the femur, and the like using X-ray are known. If the radius is a target of measurement, for actual measurement, a predetermined region of the forearm placed and fixed on a table is irradiated with an X-ray from under the table, and the X-ray transmitting through the forearm is detected by a detector disposed within an arm portion of the device above the table for obtaining data. For a normal diagnosis, a region of interest is set using the position of an ulna styloid process as a reference. The region of interest is set in a position at a distance of 1/N (N is a natural number), more specifically, 1/10, ⅕, ⅓, for example, of a forearm length from the position of the ulna styloid process.
The bone density measuring devices for the forearm are disclosed in the following Patent Documents 1 and 2.